The aim of this study is to determine whether altered expression of CD11b (Mac-1 or CR3) on granulocytes can serve as a marker for sepsis, thereby identifying infants in need of critical therapy and sparing infants who are not at risk a costly stream of tests, procedures and medications. Whole blood samples are obtained from newborns admitted to the Neonatal Intensive Care Unit to rule out sepsis. Samples are diluted with 2.5 ml staining, and stained with Phycoerythrin-conjugated CD11b monoclonal antibody. CD11b expression on neutrophils are determined by flow cytometry. Blood is sent for routine bacterial culture, complete blood count (CBC) and C-reactive protein (CRP) determination by the hospital's diagnostic facility. Results of bacterial cultures, CBC and CRP are obtained 5 -7 days later, and are correlated with the previously determined (and thus blinded) neutrophil CD11b expression.